Since your router now correctly points to the DNS servers you've chosen, one quick thing to check is your internet connection setting - look to see that under the IPv4 tab it's set to "auto DHCP". If you've a local DNS cache done by OS, flush it.

And yes, I'd be interested in what Comodo does differently from the others. Is there something you can spot from settings or options? (I used and still recommend their firewall.)

Ok, let's try this.
Put a decent firewall on your machine such as Comodo or ZoneAlarm.
Plug your machine directly into your modem and refresh your machine's IP address.
[You may have to reboot your modem to get it to sync.]

kermidge: I have chedked the DNS settings, and they are as you've mentioned. I have "looked under the hood" of the Comodo browser, and haven't been able to determine the source of their internet wizardry, but I haven't resorted to disassembling the executable yet...

SpacemanSpiff: I have now installed Comodo Internet Security Premium (free), and am now 15h into a full anti- scan to see if there are any removable sources to my frustration, will keep the list apprised of my findings. I haven't switched from the wireless card to the wired port just yet (I have been using the wireless card because my router is maxed-out at 4 in-use ports, but this weekend I will be able to free up one of them to perform this test.) Oddily enough, though, I haven't been able to connect any of my browsers to the Internet since installing the Comodo firewall, but I want to let it finish the AV scan first, and put it through a few more reboots, before I conclude that it is making things worse rather than better. I had been running AV-free and firewall-free for the purposes of testing, which I certainly wouldn't want to do for the future.

cloudandskye: Thanks for that link. I have had my suspicions about SuperAntiSpyware for a while now, but that link clarifies it for me. Although I don't believe it to be the problem, I will be removing that from this computer, and other computers that I have it installed on. Again, if it provides any relief, I'll certainly get back to this thread.